Wiemer, Daniel, Schrank, Christoph E., Murphy, David T., Wenham, Lana, and Allen, Charlotte M. (2018) Earth's oldest stable crust in the Pilbara Craton formed by cyclic gravitational overturns. Nature Geoscience, 11. pp. 357-361.

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Abstract

During the early Archaean, the Earth was too hot to sustain rigid lithospheric plates subject to Wilson Cycle-style plate tectonics. Yet by that time, up to 50% of the present-day continental crust was generated. Preserved continental fragments from the early Archaean have distinct granite-dome/greenstone-keel crust that is interpreted to be the result of a gravitationally unstable stratification of felsic proto-crust overlain by denser mafic volcanic rocks, subject to reorganization by Rayleigh–Taylor flow. Here we provide age constraints on the duration of gravitational overturn in the East Pilbara Terrane. Our U–Pb ages indicate the emplacement of ~3,600–3,460-million-year-old granitoid rocks, and their uplift during an overturn event ceasing about 3,413 million years ago. Exhumation and erosion of this felsic proto-crust accompanied crustal reorganization. Petrology and thermodynamic modelling suggest that the early felsic magmas were derived from the base of thick (~43 km) basaltic proto-crust. Combining our data with regional geochronological studies unveils characteristic growth cycles on the order of 100 million years. We propose that maturation of the early crust over three of these cycles was required before a stable, differentiated continent emerged with sufficient rigidity for plate-like behaviour.

Item ID:	83422
Item Type:	Article (Research - C1)
ISSN:	1752-0908
Copyright Information:	© 2018 Macmillan Publishers Limited, part of Springer Nature. All rights reserved.
Date Deposited:	13 Aug 2024 00:54
FoR Codes:	37 EARTH SCIENCES > 3705 Geology > 370507 Planetary geology @ 20% 37 EARTH SCIENCES > 3705 Geology > 370511 Structural geology and tectonics @ 40% 37 EARTH SCIENCES > 3705 Geology > 370502 Geochronology @ 40%
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